Driving belt



July 8, 1930. F. H. DE BRUIN DRIVING BELT Filed May 16. 1928 F'IG:1

Patented July 8, 1930 r srrs FREDERIK HARKO be Baum, 0F 'GRONINGEN, NETHERLANDS DRIVING BELT Application filed May 16, 1928, Serial No. 278,264, and. in the Netherlands December 24, 1926.

This invention relates to driving or transmission belts and particularly to double driv-- ing belts preferably made of leather, which are superior to the ordinary double, or layer, driving belts as the same are more flexible and also possess other advantages. The usual double driving belts consist of alower and upper strap adhesively held together along the entire length. Said belts are very stiff, and their period of usefulness is comparatively short, especially when they run over small pulleys. It has been found, in practice, that with such double belts the lower strap which runs over the pulley becomes torn after a short time. The double belt according to this invention consists of an upper and lower strap, each of the same kind of leather, and the parts which form the upper and lower straps are glued together in the usual manner with a waterproofglue, the upper and lower straps being joined together by means of rustpro-of hollow nails or rivets.

The advantages of the belt according to the present invention are the following As the upper and lower straps are not adhesively held together, but are riveted together, the double belt retains the flexibility of a single belt and is, therefore, particularly suitable to run over small pulleys. The belt according to this invention may also be used on smaller pulleys, as has hitherto been found practicable with double belts. @wing to its great flexibility, the belt lies much better on the pulley than the usual double belt. The adhesion is considerably greater and about the same as in the case of single belts. Therefore, with a belt according to this invention,

greater power can be transmitted than with the usual adhesively held double belts. The

belt is, therefore, suitable for any speed permissible on small pulleys. As the belt according to this invention is perforated along its entire length, and the air between the pulley and belt can easily escape through the hollow nails or rivets, the belt will lie properly on' the pulley and run smoothly and without jerks. The upper and lower belts are made of similar material. The hollow nails or rivets are introduced through holes punched in the double belt and are turned and pressed outwardly on the lower edge in such manner that their lower edges lie within the lower surface of the lower strap, a stufiingbeing provided between the nails or rivets. The lower strap thus rests with leather cushions on the pulley, so that the ends or heads of the nails or rivets do not come in contact with the pulley. r In the drawing, which illustrates one method of carrying the inventionlintoefiect Figure 1 represents a cross-section through I a double belt constructed according'to the present invention having a fewhollow nails fixed therein.

Figure 2 is a top view of a portion of the belt. 7

Figure 3 is a perspective viewfrom below of a portion of the belt. .The upper beltl isconnected with the lower belt 3 by means of hollow nails or rivets 2. The lower'edge of the nail is turned up or beaded, as shown at 4, and pressed and knocked in such manner that the lower ends of the nails or rivets lie within the lower surface of the lower strap. Cushions or slightly bulged portions 5 are thus formed as shown in Figures 1 and 3.

' What I claim is Atwo-layer' driving belt composed of an upper andlower strap each of the same thickness and width and of material having the same tensile strength, the parts of each of 1 

